The Eye
The Eye Diagram
Major Functions of the Eye
1. Gathers, Focuses, and Transmits
light through a lense to create an
image of the environment.
Major Parts/ Function( eye)
Lens - a crystalline structure located just
behind the iris - it focuses light onto the retina
Optic nerve - the nerve that transmits electrical
impulses from the retina to the brain
Major Parts/ Function( eye)
Pupil - the opening in the center of the iris- it changes size
as the amount of light changes (the more light, the smaller
the hole)
Retina - sensory tissue that lines the back of the eye. It
contains millions of photoreceptors (rods and cones) that
convert light rays into electrical impulses that are relayed to
the brain via the optic nerve
Major Parts/ Function( eye)
Cornea - the clear, dome-shaped tissue
covering the front of the eye.
Iris - the colored part of the eye - it controls the
amount of light that enters the eye by changing
the size of the pupil
Parts of the Retina
Rods- Cells in the Retina that sense brightness.
Night vision involves mostly rods. There are
many more rods than cones.
Cones- Cells in the Retina that sense color. 3
types. L, M, and S.
Ted Ed Color
Path Light takes From Eye to Brain
Light rays enter the eyes by passing through
the cornea, the pupil, the lens, the vitreous, and
then striking the light sensitive nerve cells
(rods and cones) in the retina.
Path Light takes From Eye to Brain
Interactions with other Systems
1.Nervous System- by sending signals from
eye to brain through the optic nerve.
2.Muscular System- Moves the eye lids for
protection and Eye ball for vision.
3.Circulatory System- Transmits blood and
nutrients allow the eye to function.
Facts (eye)
20/20 vision- Normal human vision, a condition
in which a person can see a letter of a specific
size from a distance of 20 feet.
Binocular vision- The coordinated use of two
eyes which gives the ability to see the world in
three dimensions. 3D
Facts ( eye) Ted Ed
Glasses
Nearsighted- called myopia. a condition in which nearby
objects are seen more clearly then distant objects because
the light is focused in front of the retina, and not on it.
Facts ( eye)
Farsighted- called hyperopia. A condition in which distant
objects are seen more clearly than nearby objects because
light is focused behind the retina, and not on it
The Ear
Major Functions of the Ear
1.Hearing of Outside stimuli (Sound Waves)
2. Maintaining Balance
Major Parts/ Function (ear)
Hammer- a tiny bone that passes vibrations from
the eardrum to the anvil.
Anvil- a tiny bone that passes vibrations from the
hammer to the stirrup.
Major Parts/ Function (ear)
Stirrup- a tiny, U-shaped bone that passes
vibrations from the anvil to the cochlea. This is the
smallest bone in the human body ( 0.25 to 0.33 cm
long.)
Major Parts/ Function (ear)
Outer Ear Canal- The tube through which sound
travels from the Pinna to the eardrum.
Eardrum- (Also called the tympanic membrane) a
thin membrane that vibrates when sound waves
reach it.
Major Parts/ Function (ear)
Pinna- The visible part of the outer ear. It collects
sound and directs it into the outer ear canal.
Cochlea- A spiral-shaped, fluid-filled inner ear
structure; it is lined with cilia (tiny hairs) that move
when vibrated and cause a nerve impulse to form
-
Major Parts/ Function (ear)
Semicircular Canals- Three loops of fluid-filled
tubes that are attached to the cochlea in the inner
ear. They help us maintain our sense of balance.
Eustachian tube- A tube that connects the middle
ear to the back of the nose; it equalizes the pressure
between the middle ear and the air outside.
Major Parts/ Function (ear)
Auditory nerve- These carry electro-chemical
signals from the inner ear (the cochlea) to the brain.
-
The Ear Diagram
The Ear-like this one?
Or this one?
Path Sound takes From Ear to Brain
Interactions with other Systems
1.Nervous System- by carrying nerve
impulses from semicircular canal to brain.
Through the auditory nerve
2.-3. Muscular/ Skeletal System - To provide/
maintain balance.
Facts (EAR)
Skin glands in the ear canal produce ear wax which helps
protect the ear by lubricating it and cleaning it of dirt and dust.
The inner ear is found inside the temporal bone, the hardest
bone in the human body.
The middle ear also contains the Eustachian tube which helps
equalize pressure and drain mucus.
Abnormalities in the inner ear of humans can cause deafness.